What fertilizer produces the best harvest?
Written by
Liu Xiaohui
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.When you plant zucchini, the choice of fertilizer will determine whether you are harvesting baseball bats or tender squash. I had a client who loved to use 20-10-10 fertilizer so much, she produced huge zucchini leaves and zero fruit. You will not get balance if you overload zucchini with fertilizer because zucchini needs some specific nutrients and growth stages to be productive.
Early Growth (Weeks 1-3)
- 10-10-10 NPK for root/leaf development
- Apply 1/2 cup per plant at planting
- Side-dress with fish emulsion weekly
Flowering Phase
- Switch to 5-10-10 NPK
- Boost phosphorus for blossom set
- Foliar spray compost tea biweekly
Fruit Development
- Maintain 5-10-10 + calcium
- Add gypsum if soil Ca < 200 ppm
- Reduce nitrogen to prevent hollow fruits
Calcium deficiencies are brutely evident, in one night, I have seen perfectly fine zucchini rot away from the blossom end. Test soil calcium 30 days later. If you need a quick fix, take, eggshells, crush them, put them in some vinegar overnight, and dilute 1:10 and use it as a foliar spray. Spray in the evening so the leaves do not burn.
Organic Boosters
- Worm castings: 2% N, 1% P, 1% K
- Bone meal: 4-12-0 for phosphorus
- Kelp meal: 1-0-2 + trace minerals
Mineral Supplements
- Gypsum: 23% Ca, 18% S
- Epsom salts: 10% Mg for chlorophyll
- Greensand: 3% K + iron
Over-applying nitrogen fertilizer attracts squash bugs as they can smell overzealous vegetation. My clients in Arizona lowered their squash bug infestation by 60% by dropping the 5% N for fertilizer. Fertilizers will also leach from your soil when complemented with drip irrigation.More next week when we expose different pest control hacks that coincide with your feed regime.
Read the full article: When to Plant Zucchini: Perfect Timing for Big Harvests
